Cellen 2

Data visualisation — introduction

Gavin Simpson
gavin@anivet.au.dk

Aarhus University

2025-02-20

Learning objectives

At the end of this topic you should

  • Understand the basic principles of data visualization

Data Visualization

Some data visualizations are better than others

Data Visualization

Some data visualizations are better than others

  • Taste
    • The eye is in the beholder
  • Choice of data
  • Human visual perception

What makes bad figures?

Aesthetic

Tacky, tasteless, ugly, hodgepodge, inconsistent design

Substantive

Graph has problems because of the data being presented

Perceptual

Inspite of good taste and good data, a graph may be confusing or misleading because of how people perceive and process what they are looking at

Always plot your data

  • Anscombe’s quartet
  • Scatterplot
    • 2 quantities mapped to x and y axis
  • \(x\) and \(y\) in each set have the same
    • mean
    • variance
  • Regression lines have same \(\hat{\beta}\)
  • \(x\) and \(y\) have the same correlation

Visualising data

Visualising data

Visualising data

Bad data

Bad data

Bad Data